September 10, 2003
Elvia H. Thompson
Headquarters, Washington
(Phone: 202/358-1696)
Rob Gutro
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-4044)
Alan Buis
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-0474)
RELEASE: 03-288
NASA SATELLITES SAMPLE HURRICANE "INGREDIENTS" TO HELP FORECASTERS
Image Left: Hurricane Fabian.
The Atlantic Ocean becomes a meteorological mixing bowl from June 1 to
November 30, replete with all the needed ingredients for a hurricane
recipe. NASA turns to its cadre of satellites to serve up a feast of
information to the forecasters who seek to monitor and understand
these awesome storms.
Typically, during the peak of hurricane season, from late August to
mid-September, tropical cyclones of interest to U.S. coastal regions
form around the Cape Verde Islands off Africa. NASA satellites are
critical for helping forecasters determine if all of the ingredients
are coming together to create a hurricane. If a hurricane forms, it
is critical to know how strong it may be and which coastal
communities or sea lanes will be at risk.
NASA provides researchers and forecasters with space-based
observations, data assimilation, and computer climate modeling.
NASA-sponsored measurements and modeling of global sea surface
temperature, precipitation, winds and sea surface height have also
improved understanding of El Nino and La Nina events, which
respectively tend to suppress and enhance Atlantic and Gulf hurricane
development.
Thirty years ago, meteorologists were unable to see the factors in
hurricane formation and could only spot a hurricane with still
pictures from the TIROS-N satellite. Over the past 10 years, visible
and infrared satellite sensors were the workhorses for monitoring
hurricanes. Today, multiple NASA satellites exploit everything from
radar pulses to microwaves to enhance forecasts, providing data to
researchers several times a day.
The first ingredient in the hurricane recipe is sea surface
temperature of at least 82 F. Unlike traditional infrared satellite
instruments, the Aqua satellite's Advanced Microwave Scanning
Radiometer (AMSR-E) and the Tropical Rainfall Measuring Mission's
(TRMM) Microwave Imager can detect sea surface temperatures through
clouds. This valuable information can help determine if a tropical
cyclone is likely to strengthen or weaken. The Jason-1 satellite
altimeter provides data on sea surface height, a key measurement of
ocean energy available to encourage and sustain hurricanes.
Another necessary ingredient is rotating winds over the ocean's
surface, precursors to tropical cyclone development. The
NASA-provided SeaWinds instruments aboard Japan's Midori 2 and NASA's
QuikSCAT satellites can detect these winds before other instruments,
providing even earlier notice of developing storms to forecasters and
scientists.
Air temperature and humidity are also important factors. The
Atmospheric Infrared Sounder (AIRS) experiment suite aboard the Aqua
satellite obtains measurements of global temperature and humidity
throughout the atmosphere. This may lead to improved weather
forecasts; improved determination of cyclone intensity, location and
tracks; and the severe weather associated with storms, such as
damaging winds.
Rainfall intensity is the final ingredient, and the Precipitation
Radar provided by Japan for the TRMM satellite provides CAT scan-like
views of rainfall in the massive thunderstorms of hurricanes. TRMM
instruments probe young tropical systems for rainfall intensity and
the likelihood of storm development. TRMM also sees "hot towers" or
vertical columns of rapidly rising air that indicate very strong
thunderstorms. These towers are like powerful pistons that convert
energy from water vapor into a powerful wind and rain-producing
engine. Once a storm develops, TRMM provides an inside view of how
organized and tightly spiraled rain bands are, key indicators of
storm intensity.
TRMM provides tropical cyclone intensity information from the safe
distance of space allowing the National Oceanic and Atmospheric
Administration's (NOAA) National Hurricane Center and the Department
of Defense Joint Typhoon Warning Center to turn to TRMM, QuikSCAT and
other NASA satellites for early assessment of storms in the open
ocean.
The hurricane monitoring capabilities enabled by these satellites are
funded by NASA's Earth Science Enterprise, which is dedicated to
understanding the Earth as an integrated system and applying Earth
System Science to improve prediction of climate, weather, and natural
hazards using the unique vantage point of space.
For more information and NASA images on the Internet, visit:
http://www.gsfc.nasa.gov/topstory/2003/0909hurricane.html
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